Set up Windows unit test CI

[GregoryComer]

Run the unit test CI on Windows.

[GregoryComer]

I've worked through the CI setup issues and have the unit tests running .PR should be ready for review tomorrow - targeting land by EOW. Running locally, I've got ~95% of the unit tests passing. I'm working through the remaining issues. Most things have worked out of box once the build passed, but there have been a few things to clean up. Incorrect paths for loading custom op libs, env setup for dynamo are the most common.

[GregoryComer]

#13923 is merged, which should be the final PR. We have both Python and native unit tests running in CI. I'm tracking a few final follow-ups in #13883, but we should be good to consider this done for the purposes of GA.